Gaurav Saxena

Environmental Pollution, Toxicity Profile and Treatment Approaches for Tannery Wastewater and Its Chemical Pollutants

Leather industries are key contributors in the economy of many developing countries, but unfortunately they are facing serious challenges from the public and governments due to the associated environmental pollution. There is a public outcry against the industry due to the discharge of potentially toxic wastewater having alkaline pH, dark brown colour, unpleasant odour, high biological and chemical oxygen demand, total dissolved solids and a mixture of organic and inorganic pollutants. Various environment protection agencies have prioritized several chemicals as hazardous and restricted their use in leather processing however; many of these chemicals are used and discharged in wastewater. Therefore, it is imperative to adequately treat/detoxify the tannery wastewater for environmental safety. This paper provides a detail review on the environmental pollution and toxicity profile of tannery wastewater and chemicals. Furthermore, the status and advances in the existing treatment approaches used for the treatment and/or detoxification of tannery wastewater at both laboratory and pilot/industrial scale have been reviewed. In addition, the emerging treatment approaches alone or in combination with biological treatment approaches have also been considered. Moreover, the limitations of existing and emerging treatment approaches have been summarized and potential areas for further investigations have been discussed. In addition, the clean technologies for waste minimization, control and management are also discussed. Finally, the international legislation scenario on discharge limits for tannery wastewater and chemicals has also been discussed country wise with discharge standards for pollution prevention due to tannery wastewater.

Microbial indicators, pathogens and methods for their monitoring in water environment

Water is critical for life, but many people do not have access to clean and safe drinking water and die because of waterborne diseases. The analysis of drinking water for the presence of indicator microorganisms is key to determining microbiological quality and public health safety. However, drinking water-related illness outbreaks are still occurring worldwide. Moreover, different indicator microorganisms are being used in different countries as a tool for the microbiological examination of drinking water. Therefore, it becomes very important to understand the potentials and limitations of indicator microorganisms before implementing the guidelines and regulations designed by various regulatory agencies. This review provides updated information on traditional and alternative indicator microorganisms with merits and demerits in view of their role in managing the waterborne health risks as well as conventional and molecular methods proposed for monitoring of indicator and pathogenic microorganisms in the water environment. Further, the World Health Organization (WHO) water safety plan is emphasized in order to develop the better approaches designed to meet the requirements of safe drinking water supply for all mankind, which is one of the major challenges of the 21st century.

Characterization and Identification of Recalcitrant Organic Pollutants (ROPs) in Tannery Wastewater and Its Phytotoxicity Evaluation for Environmental Safety

Tannery wastewater (TWW) is of serious environmental concern to pollution control authorities, because it contains highly toxic, recalcitrant organic and inorganic pollutants. The nature and characteristics of recalcitrant organic pollutants (ROPs) are not fully explored to date. Hence, the purpose of this study was to characterize and identify the ROPs present in the treated TWW. Gas chromatography–mass spectrometry data analysis showed the presence of a variety of ROPs in the treated TWW. Results unfolded that benzyl chloride, butyl octyl phthalate, 2,6-dihydroxybenzoic acid 3TMS, dibutyl phthalate, benzyl alcohol, benzyl butyl phthalate, 4-chloro-3-methyl phenol, phthalic acid, 2′6′-dihydroxyacetophenone, diisobutyl phthalate, 4-biphenyltrimethylsiloxane, di-(-2ethy hexyl)phthalate, 1,2-benzenedicarboxylic acid, dibenzyl phthalate, and nonylphenol were present in the treated TWW. Due to endocrine disrupting nature and aquatic toxicity, the U.S. Environmental Protection Agency classified many of these as “priority pollutants” and restricted their use in leather industries. In addition, the physicochemical analysis of the treated TWW also showed very high BOD, COD, and TDS values along with high Cr and Pb content beyond the permissible limits for industrial discharge. Furthermore, phytotoxicity assessment unfolds the inhibitory effects of TWW on the seed germination, seedling growth parameters, and α-amylase activity in Phaseolus aureus L. This indicates that the TWW discharged even after secondary treatment into the environment has very high pollution parameters and may cause a variety of serious health threats in living beings upon exposure. Overall, the results reported in this study will be helpful for the proper treatment and management of TWW to combat the environmental threats.

Ram Chandra: advances in biodegradation and bioremediation of industrial waste

Environmental sustainability with rapid industrialization is one of the major challenges of the current scenario worldwide (Chandra 2015). Industries are the key drivers in the world economy, but these are also the major polluters due to discharge of hazardous wastes containing organic and inorganic pollutants, which cause environmental (soil and water) pollution and severe toxic effects in living beings (Maszenan et al. 2011; Chandra 2015). Being a low cost and eco-friendly clean technology, bioremediation can be a sustainable alternative to conventional technologies for the treatment and management of industrial wastes to protect the environment and human health (Megharaj et al. 2011; Maszenan et al. 2011). Bioremediation utilize microorganisms, plants or their enzymes to degrade/detoxify the pollutants in the environment (Kulshreshtha 2012). However, the mechanism of bioremediation technologies and their role in the environmental cleanup is in nascent stage. Therefore, in this perspective, the book, ‘‘Advances in Biodegradation and Bioremediation of Industrial Waste’’ provides a comprehensive knowledge on the fundamental, practical, and purposeful utilization of bioremediation technologies for the sustainable development. The book describes the microbiological, biochemical, and molecular aspects of biodegradation and bioremediation, including the use of microbial genomics and proteomics for the development of efficient bioremediation technologies for industrial wastes to combat the forthcoming challenges. The book contains 14 chapters exclusively focused on the different aspects of biodegradation and bioremediation of industrial wastes. Each chapter is concluded with an exhaustive list of references for readers interested to learn further details about the subject matter. All the chapters are accessible through internet to readers who would find this book most useful. For this book, many relevant topics have been contributed by the experts from different universities, research laboratories, and institutes. In general, the book is outstanding, except Chap. 11, which mainly describe the anaerobic biodegradation of tallow-slaughterhouse lipid (TSHL) waste. The first chapter highlights the basic mechanisms used by plants in phytoremediation of heavy metals (HMs) from industrial waste polluted sites for environmental cleanup. In addition, the role of siderophore-producing plant growth promoting rhizobacteria in bioremediation and potential of genetically engineered plants that possess the required traits necessary under certain environmental conditions has been also discussed. Further, the phytoremediation has been suggested as a low cost alternative for developing countries like India, where funding is a big issue. The potential of microbial cells (dead or alive) as biosorbents for HMs removal from industrial wastewaters has been discussed in Chap. 2. The mechanisms used by microbial cell biosorbents and innovations to both live and dead cells through immobilization; growth manipulation and genetic engineering have been well described through figures in this chapter. Chapter 3 presents an overview on the toxicity, microbial degradation, and degradation pathways of polycyclic aromatic hydrocarbons (PAHs) and pesticides from industrial wastes for sustainable environment. Enzymes are crucial for all life forms and play an important role in the biodegradation and bioremediation of & Ram Naresh Bharagava bharagavarnbbau11@gmail.com; ramnaresh_dem@bbau.ac.in

Applications of Metagenomics in Microbial Bioremediation of Pollutants

Abstract Environmental pollutants are of serious ecotoxicological and health concern worldwide. To cope with these, bioremediation technologies utilizing microorganisms is currently viewed as an excellent cost-effective and ecofriendly strategy for the environmental management. However, a strategic execution of the bioremediation technology requires the knowledge of microbial metabolism, key enzymes, and genes involved and nature, dynamics, and composition of microbial communities, which can be easily understood by applying molecular techniques. Conventional or culture-dependent molecular techniques are currently being applied to characterize the potential pollutants degrading/detoxifying microbes, but these techniques are sometimes biased and do not actually provide the accurate information. However, the currently emerging metagenomic approaches including next-generation sequencing technologies can provide the reliable information and reveal very useful information about the metagenome of environmental microorganisms, which play an important role in the biogeochemical cycles and degradation and detoxification of environmental pollutants using culture-independent molecular techniques. Therefore, this chapter provides an overview of the metagenomic approaches and their applications in microbial ecology and bioremediation.